IL-2 receptors on rabbit T-cell lines and their transfectants expressing the human IL-2 receptor alpha chain.
Low-affinity (dissociation constant: Kd = 7 nM) and high-affinity (Kd = 27 pM) interleukin-2 receptors (IL-2R) were detected on rabbit T-cell lines by IL-2 binding studies. Chemical cross-linking studies using 125I-labelled IL-2 showed that rabbit low-affinity IL-2R was singly expressed alpha-chain (MW 55,000) and that high-affinity IL-2R was composed of at least alpha- and beta- (MW 75,000) chains, similar to the human and murine counterparts. The existence of an additional chain (MW 25,000) was suggested in the rabbit IL-2R. Rabbit T-cell transfectant lines were established by human IL-2R alpha-chain (IL-2R alpha) cDNA transfection. These transfectant lines possessed not only extremely large numbers of human IL-2R alpha (over 10 times more than endogenous rabbit alpha-chain) but also twice as many high-affinity sites as their parental lines. The number of high-affinity sites on the transfectants significantly decreased when human alpha-chains were blocked, indicating that these transfectants expressed high-affinity receptor consisting of the exogenous human alpha-chain and rabbit beta-chain. This was confirmed by cross-linking experiments. The observation that expression of extremely large numbers of exogenous alpha-chains lead to an increase of the total number of high-affinity sites in the apparent absence of an increase of beta-chain expression raises the possibility that not only the beta-chain but also the alpha-chain may play an important role in regulating the number of high-affinity receptors.
Yamamura
Y
Y
Department of Immunology, Tokyo Metropolitan Institute of Medical Science, Japan.
Kotani
M
M
Tsudo
M
M
Karasuyama
H
H
Seto
A
A
Miyasaka
M
M
D000818:Animals; D002460:Cell Line; D005434:Flow Cytometry; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism; D008970:Molecular Weight; D011817:Rabbits; D015375:Receptors, Interleukin-2 / Q000032:analysis* / Q000235:genetics; D013601:T-Lymphocytes / Q000276:immunology*; D014162:Transfection / Q000276:immunology*
D007376:Interleukin-2; D015375:Receptors, Interleukin-2